LOS ANGELES — When he wasn't busy scribbling out the theory of relativity, Albert Einstein seems to have spent a fair amount of time writing letters involving topics such as God, his son's geometry studies, even a little toy steam engine an uncle gave him when he was a boy.
More than two dozen of Einstein's letters were sold on Thursday at the California-based auction house Profiles in History, for a total of $420,625. That figure includes a 25 percent buyer's premium. Auction associate Kayla Sues told NBC News that the identities of the buyers were confidential.
Amassed over decades by a private collector, the letters represent one of the largest caches of Einstein's personal writings ever offered for sale. But more than that, they give a rare look into Einstein's thoughts when he wasn't discussing complicated scientific theories with his peers.
In one letter, Einstein urged one of his sons to get more serious about geometry. In another, he consoled a friend who recently discovered her husband's infidelity. In still another to an uncle on his 70th birthday, Einstein recalled how the toy steam engine the uncle gave him years ago had prompted a lifelong interest in science.
On the issue of God, Einstein dismissed the widely held view that he was a confirmed atheist. "I have repeatedly said that in my opinion the idea of a personal God is a childlike one," he wrote to a man who corresponded with him on the subject twice in the 1940s. "You may call me an agnostic, but I do not share the crusading spirit of the professional atheist. ... I prefer an attitude of humility corresponding to the weakness of our intellectual understanding of nature and of our own being."
Lot by lot, the letters fetched prices ranging from $6,875 to $62,500 — but Joseph Maddalena, the founder of Profiles in History, said he considered them priceless. "These are certainly among the most important things I've ever handled," Maddalena said. "This is not like a Babe Ruth autograph or a signed photo of Marilyn Monroe. These are historically significant."
The auction also featured the sale of other historical memorabilia and documents, including a handwritten copy of the 13th Amendment to the U.S Constitution that was signed by 125 members of Congress. That 1865 document, which called for the abolition of slavery throughout the nation, sold for $187,500.
Marc Kruskol, a spokesman for Profiles in History, told NBC News in an email that Thursday's auction rang up more than $2 million in total sales.
This Associated Press report was updated by NBC News. An earlier version of this report did not include the customary buyer's premium in the total tally. Before the premium was added, the sales of the Einstein letters tallied up to $336,500.